Thermal transport across graphene and single layer hexagonal boron nitride

Abstract

As the dimensions of nanocircuits and nanoelectronics shrink, thermal energies are being generated in more confined spaces, making it extremely important and urgent to explore for efficient heat dissipation pathways. In this work, the phonon energy transport across graphene and hexagonal boron-nitride (h-BN) interface is studied using classic molecular dynamics simulations. Effects of temperature, interatomic bond strength, heat flux direction, and functionalization on interfacial thermal transport are investigated. It is found out that by hydrogenating graphene in the hybrid structure, the interfacial thermal resistance (R) between graphene and h-BN can be reduced by 76.3%, indicating an effective approach to manipulate the interfacial thermal transport. Improved in-plane/out-of-plane phonon couplings and broadened phonon channels are observed in the hydrogenated graphene system by analyzing its phonon power spectra. The reported R results monotonically decrease with temperature and interatomic bond strengths. No thermal rectification phenomenon is observed in this interfacial thermal transport. Results reported in this work give the fundamental knowledge on graphene and h-BN thermal transport and provide rational guidelines for next generation thermal interface material designs.

Ultrafast relaxation of hot phonons in graphene-hBN heterostructures

“…The interaction between the carriers in graphene and the surface plasmon polaritons (SPP) of the polar substrate has been proposed as a possible cooling mechanism for overcoming the HP bottleneck in graphene. [15][16][17]34 It has been established that graphene on hBN substrates has lower charge doping level than graphene on SiO 2 3 which is also the case in our samples as evidenced by the slightly upshifted (∼10 cm 1 ) and narrower G peak 27 36 4 800 Room temperature, theoretical Chen et al 33 7.41 435 Room temperature, experimental Zhang et al 37 3 1076 200-700 K, theoretical Ting Li et al 38 1-10 300-3000 200-600, theoretical the dominant cooling mechanism, the doping of graphene due to SiO 2 will shield this interaction and reduce the efficacy of this channel consequently increasing the relaxation time for phonons in g-SiO 2 . The interaction between graphene and the substrate also depends on many factors like topographic conformity, Coulombic interactions, and adhesion energy.…”

Thermal Boundary Conductance and Phonon Transmission in Hexagonal Boron Nitride/Graphene Heterostructures

“…The observed trend with temperature may be a result of the ZA branch in ab ‐axis and LA branch in c ‐axis (i.e., TL2 branch), being the dominant contributor to TBC for both A‐DMM and PWA‐DMM models. The maximum frequency of vibrations (Table S1, Supporting Information) for the two branches corresponds to Debye temperatures of 764 and 174 K, respectively, but the contribution from both remains constant above 200 K. Zhang et al used MD simulations to show increased TBC from 200 to 700 K which the authors attributed to contributions from high‐frequency phonons at elevated temperatures. Our implementation of the DMM only includes the contributions of acoustic phonons which are the dominant heat carriers in the h‐BN/G material system due to the large DOS for ZA phonons at low frequencies .…”

“…The maximum frequency of vibrations (Table S1, Supporting Information) for the two branches corresponds to Debye temperatures of 764 and 174 K, respectively, but the contribution from both remains constant above 200 K. Zhang et al used MD simulations to show increased TBC from 200 to 700 K which the authors attributed to contributions from high‐frequency phonons at elevated temperatures. Our implementation of the DMM only includes the contributions of acoustic phonons which are the dominant heat carriers in the h‐BN/G material system due to the large DOS for ZA phonons at low frequencies . Frequency‐dependent phonon transmission and TBC reported by Yan et al have revealed this fact in vertically stacked h‐BN/G/h‐BN interfaces with the large DOS mismatch resulting in smaller transmission at high frequencies.…”

“…The TBC at graphene/h‐BN interfaces has been reported recently . Using first‐principles atomistic Green's function (AGF) simulations, Mao et al reported a room temperature (RT) TBC of 187 MW m −2 K −1 for a multilayer graphene/multilayer h‐BN structure.…”

“…Using first‐principles atomistic Green's function (AGF) simulations, Mao et al reported a room temperature (RT) TBC of 187 MW m −2 K −1 for a multilayer graphene/multilayer h‐BN structure. Zhang et al estimated the TBC at graphene nanoribbon/h‐BN bilayer structure to be 5 MW m −2 K −1 at RT using classical molecular dynamics (MD) simulations. Yan et al used first‐principles simulations to study the effect of stacking arrangement on TBC for monolayer graphene sandwiched between layers of h‐BN.…”